this question will probably make me a fool but here goes. recently purchased vanguard hog reaper in 308,vortex diamondback and mounts, shoots 3 inches low @ 100 yards and out of scope adjustment,all the way up. scope centerline is one inch above barrel? its got to be my age taking over. can someone help this old fool out. I have mounted many scopes in my day. what did I do wrong.